This invention relates to a planer provided with means for reducing the noise emitted by the blade-retaining shaft. The invention is especially useful in reducing the noise emitted by wood planers.
The tool bit holder shafts of conventional wood planing machines comprise generally a cylindrical shaft arranged for rotation about a horizontal axis, wherein one or more seats with longitudinal and radial lay are formed to receive the tool bits, e.g. blades. Such blades are secured in the respective seats by means of gibs (strips) and bolts, such that the cutting edges project from the cylindrical shaft surface to permit removal of wood shavings.
The blade carrying shaft is pivotally supported in a chamber which is open at the working surface area where the blades are brought into contact with the work-piece.
The main portion of the noise generated by a shaft of this kind is due to the impact of the blade portion protruding from the outer surface of the shaft with the surrounding air, as the blades move past the apertured area of the table or working surface. The quick succession of such impacts and the repeated expansions and compressions of the air at said area produce a noise which is both disturbing and harmful for the planer operator(s), it reaching occasionally untolerably high levels.